Water Balance Assessment of Catchments in Pyroclastic-Covered landslide prone areas of Campania (Italy): A Budyko model application

Geo-hydrological hazards induced by rainfall in small catchments, such as landslides, debris flows and flash floods, represent serious risks to infrastructure and human worldwide. These phenomena are typically triggered by periods of heavy rain, with geomorphological features and antecedent soil and groundwater storage of the catchment as contributing factors(Bogaard & Greco, 2018). The assessment of water balance at the catchment scale may help to highlight the role played by different hydrological processes on the occurrence of these geohazards. In southern Italy's Campania region, steep slopes are covered by loose granular deposits covering a karstic limestone bedrock, making them particularly prone to shallow landslides. Over the past few decades, this region has indeed experienced some catastrophic landslides triggered by rainfall(Greco et al., 2021).

In this study, the water balance of landslide-prone catchments in Campania is modelled with a simplified lumped hydrological approach, based on the Budyko framework, by exploiting data from both meteorological and hydrological sources. Ground-based and satellite data between 2002-2022 have been considered for meteorological and geographic factors. The data include precipitation and stream water level obtained from the Multi-Risk Functional Center of the Civil Protection of Campania Region, and the actual evapotranspiration data sourced from TERRA Climate (Ning et al., 2024). Moreover, the groundwater recharge is estimated by using the Turc formulation, which is effective for semi-arid and temperate climates(Allocca et al., 2014), while stream runoff is derived from observed water levels of stream by Civil Protection website of Campania region.

The results provide insights into the interactions between precipitation, evapotranspiration, groundwater recharge, infiltration capacity of soil and stream runoff in the study area. Comparing the recorded landslide occurrences recorded (Calvello and Pecoraro, 2018; Peruccacci et al., 2023) with the water balance highlights the value of hydrological information in landslide hazard assessment.